Propeller fan

ABSTRACT

1,210,141. Axial-flow and centrifugal fans. PAPST-MOTOREN K.G. March 5, 1968 [March 16, 1967], No.10668/68. Heading F1C. [Also in Division H2] In a ventilation fan such as for cooling communications apparatus, comprising an electric motor having a stator 8, 9 and a rotor 1 comprising laminations 4 having exposed external surfaces defining an annular periphery, affixed directly to circumferentially spaced portions if the latter is a plurality of blades 13 of heat conducting material e.g. metal which withdraw heat from the rotor when the motor is energized. The blades may also exchange heat with one or both metal end rings 1a, 1b and may be integral, with, or resistance welded to, the laminations 4, considerable pressure being applied during the welding process. In Figs.3 and 4 (not shown), the blades are shaped as the vanes of a paddle wheel, and V-shaped. The fan may be of centrifugal type, Fig.3 (not shown).

March 11, 1969 Ps 3,431,978

PROPELLER FAN Filed May 15, 1967 Inventor.-

United States Patent P 41,652 US. Cl. 17 0159 9 Claims Int. Cl. F04d 25/06 ABSTRACT OF THE DISCLOSURE The blades of a propeller fan consist of sheet metal and are resistance welded directly to the laminations of the rotor which surrounds the stator. Each blade is welded to each lamination and the welding operation is carried out while the blades are pressed against the rotor with a force'which suffices to effect slight penetration of blades into the external surfaces of laminations and to thus insure satisfactory exchange of heat when the fan is in use.

Background 0 the invention The present invention relates to propeller fans. More particularly, the invention relates to improvements in propeller fans wherein the rotor preferably accommodates the stator. Still more particularly, the invention relates to improvements in propeller fans which may be utilized for ventilation and efficient withdrawal of heat from electrical apparatus, for example, for cooling of apparatus which are used in the field of communications.

Many electronic components which are used in the field of telecommunications must be cooled by resorting to fans. Such electronic components are often accommodated in small areas and their efiiciency and/or life expectancy often depends on the effectiveness of ventilation. As a rule, the cooling is effected by small propeller fans, especially when it is desired to maintain the temperature of semiconductors or other critical components within a permissible range.

Presently known propeller fans are not entirely satisfactory, mainly because they do not embody an efiicient system for preventing overheating of their motors. Thus, heat developing in the rotor when the fan is in use cannot be dissipated without resorting to bulky, costly and complicated ventilating systems which often necessitate such increases in dimensions of the fans that they cannot be fitted into relatively small areas which are available therefor in electrical or electronic equipment. For example, many presently known propeller fans are provided with cylinders of plastic or metallic material which are fitted onto the rotor and carry plastic or metallic blades. Such cylinders form barriers which prevent rapid exchange of heat between the rotor and the surrounding air even if the cylinders consist of metallic material.

Accordingly, it is an important object of my invention to provide a novel and improved propeller fan wherein the rotor can be ventilated and cooled with greater efficiency than in presently known fans and wherein such efiicient cooling does not necessitate any increases in the dimensions of the fan.

Another object of the invention is to provide a propeller fan wherein the rotor can exchange heat directly with the blades.

A further object of the invention is to provide a propeller fan which can be constructed at a cost which is less than the cost of presently known propeller fans.

A concomitant object of the invention is to provide a novel method of producing a propeller fan.

An ancillary object of the invention is to provide a 3,431,978 Patented Mar. 11, 1969 method of insuring satisfactory exchange of heat between the rotor and the blades of a propeller fan.

Another object of the invention is to provide a method according to which a propeller fan can be assembled of fewer component parts than presently known propeller fans without adversely affecting the cooling of the rotor.

A further object of the invention is to provide a propeller fan which can be produced and assembled at a cost which is less than the cost involved in the manufacture of conventional propeller fans.

Summary of the invention One feature of my invention resides in the provision of a method of producing a propeller fan of the type wherein the rotor surrounds the stator. The method comprises the steps of producing the fan blades of metallic material and of connecting such blades directly to the laminations of the rotor so that the blades exchange heat with the rotor and dissipate such heat into the surrounding atmosphere when the fan is in use.

The step of connecting the blades to the laminations of the rotor is preferably carried out by resistance welding and while the blades are pressed against the external surfaces of laminations with a considerable force, preferably with a force which causes slight penetration of blades into the laminations. One electrode of the resistance welding apparatus can be used to press a blade against the laminations and the other electrode can be applied against the internal or external surfaces of the laminations. Such surfaces are preferably finished to a high degree of smoothness, for example, by turning, and are preferably of cylindrical outline.

Each blade is preferably bonded to each lamination 0f the rotor.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved propeller fan itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawing.

Brief description of the drawing FIG. 1 is a fragmentary partly elevational and partly sectional view of a conventional propeller fan;

FIG. 2 is a partly elevational and partly sectional view of a propeller fan which is constructed and assembled in accordance with a first embodiment of my invention;

FIG. 3 is a similar view of a second propeller fan with paddle-like blades; and

FIG. 4 is a similar view of a third propeller fan with V-shaped blades.

Description of the preferred embodiments FIG. 1 illustrates a portion of a conventional propeller fan. The motor of the fan comprises a rotor 1' having a package of laminations 4 and being surrounded by a substantially cylindrical casing 2 of synthetic plastic material. The casing 2 is provided with blades 3, i.e., these blades also consist of synthetic plastic material and are integral with the casing. The bearing of the rotor 1' is shown at 5', and this rotor surrounds the stator (not shown).

FIG. 2 illustrates a propeller fan which is constructed and assembled in accordance with one embodiment of the present invention. The fan comprises a substantially cylindrical shell or shroud 7 which surrounds curved metallic blades 13 and the rotor 1 of an electric motor. The laminations 8 of the stator are flanked by windings 9 and the entire stator is surrounded by the rotor 1. The blades 13 are welded to the laminations 4 of the rotor 1 in such a way that the inner edge face of each blade 13 is in heatconducting contact with each lamination of the rotor. When the circuit of the motor is completed, heat generated in the laminations 4 of the rotor 1 is conveyed radizdly outwardly, and the dissipation of heat is not hindered by a plastic casing as in the fan of FIG. 1. The blades 13 also exchange heat with the remainder of the rotor, i.e., with the two metallic rings 1a, 1b which flank the package of laminations 4. As shown, the inner edge faces of the blades 13 extend axially beyond and are welded to the rings 1a, 1b.

FIG. 3 shows a propeller fan which is constructed in accordance with a second embodiment of the present invention. The blades 16 consist of sheet metal and resemble the vanes of a paddle wheel. These blades are produced by stamping and are welded directly to the laminations 4 of the rotor which surrounds the stator in the same way as shown in FIG. 2. Each blade 14 is further Welded to at least one of the rotor rings.

The fan of FIG. 4 comprises blades 15 of V-shaped profile. The inner edge faces of these blades are welded to the laminations 4 of the rotor. An advantage of the blades 15 is that they can draw air at both ends of the shroud, i.e., the efficiency of the fan is higher. The blades 15 are welded only to the external surfaces of the laminations 4.

The blades 13, 14 or 15 are preferably secured to the laminations 4 and to the ring 1a and/or 1b of the rotor by resistance welding. Such welding is carried out while the inner edge faces of the blades are pressed against the rotor with a considerable force so that the innermost portions of the blades penetrate into the external surfaces of the laminations 4. During welding, the blades are melted or fused into the laminations to form therewith an integral unit. The laminations 4 are stacked upon each other to form a compact package. When the fan is in actual use, the blades 13, 14 or 15 perform the dual function of circulating air in the area surrounding the fan and of conveying heat from the rotor. Such heat is dissipated while the blades exchange heat with surrounding air. The area of heat exchange between the rotor (blades 13, 14 or 15) and the surrounding air is greater than in heretofore known motors for propeller fans.

In carrying out the welding operation, one electrode of the resistance welding apparatus can be used to press a blade 13, 14 or 15 against the external surfaces of the laminations 4 with a force which suffices to insure that the inner edge face of the blade is in satisfactory contact with each lamination. The other electrode is connected with the package in such a way that it remains in direct current-conducting engagement with the majority of or with all laminations 4. When the circuit is completed, the inner portion of the blade is melted and penetrates into the package to insure permanent metal-to-metal contact and highly satisfactory dissipation of heat in actual use of the fan.

The second electrode can be placed and pressed against the external surfaces of laminations 4 in immediate or close proximity of the blade which is in the process of being bonded to the rotor. Alternatively the internal surface 1c surrounding the bore in the rotor 1 (see FIG. 3) can be placed onto one electrode while the other electrode presses a blade against the external surfaces of the laminations. It is preferred to finish the internal and/ or external surfaces of laminations 4 by resorting to a precision finishing tool, for example, in a suitable turning machine.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by

applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of my contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

I claim:

1. A propeller fan, comprising a motor having a stator and a rotor, said rotor comprising laminations having exposed external surfaces which together define a composite annular peripheral surface exposed to the ambient atmosphere; and a plurality of discrete blades respectively directly afiixed to circumferentially spaced portions of said peripheral surface so that the latter is unobstructed intermediate said portions, said blades consisting at least in part of heat-conducting material to withdraw heat from the rotor when the latter rotates.

2. A propeller fan as defined in claim 1, wherein said laminations are stacked into a package having said annular peripheral surface, and wherein said blades consist of metallic material and each blade is welded directly to said annular peripheral surface.

3. A propeller fan as defined in claim 1, wherein said laminations extend in substantial parallelism with one another, each of said laminations having a radially facing outer edge face constituting one of said external surfaces, and wherein each of said blades is provided with an inner edge face afiixed directly to and in direct heatconducting contact with each of said outer edge faces.

4. A propeller fan as defined in claim 1, wherein said rotor further comprises a pair of metallic rings flanking said laminations and wherein at least some of said blades are in heat-conducting contact with at least one of said rings.

5. A propeller fan as defined in claim 1, wherein said rotor surrounds said stator.

6. A propeller fan as defined in claim 1, wherein said blades have a substantially V-shaped profile.

7. A propeller fan as defined in claim 1, further comprising a fixed shroud surrounding said blades.

8. A propeller fan as defined in claim 1, wherein said blades are constituted by metallic stampings.

9. A method of producing a propeller fan of the type wherein the blades are disposed around the rotor of the fan motor and wherein the rotor comprises metallic laminations having external surfaces, comprising the steps of making the blades of metallic material; and resistance welding the blades directly to the external surfaces of at least some laminations so that the blades exchange heat directly with such laminations when the fan is in operation.

References Cited UNITED STATES PATENTS 2,495,895 1/ 1950 Hervert. 2,742,223 4/ 1956 Font. 3,077,297 2/1963 Clarke.

FOREIGN PATENTS 973,853 6/1960 Germany. 1,031,929 6/ 1958 Germany.

EVERE'ITE A. POWELL, 1a., Primary Examiner.

US. Cl. X.R. 230-417 

